1. Field of the Invention:
The invention generally relates to energy converters and more particularly to an improved solar energy receiver particularly adapted to be mated with a Stirling engine for heating a working fluid conducted through a heat exchanger confined within the receiver, said receiver being of a separable configuration for reducing solar flux density in order to protect the heat exchanger.
As can be appreciated by those familiar with the design and operation of Stirling engines, such devices are particularly suited for utilizing solar energy in geographical areas which tend to enjoy an abundance of solar radiation. In order to more effectively utilize solar energy for powering Stirling engines, solar energy receivers often are provided for purposes of entrapping concentrated solar energy. It has been suggested that such receivers be provided with heat exchangers comprising so-called tube bundles consisting of a plurality of thin-wall tubes through which a working fluid is conveyed and thus passed through the receiver for accepting heat from the solar flux.
In practice, where the device comprises a cavity-type receiver characterized by a point focusing concentrator, it has been found that often the heat loads developed within the cavity, due to flux density, cannot be transferred to a working fluid passing through the tube bundles at a sufficiently high rate to avoid overheating. As a consequence, hot spots tend to develop in the tube walls which can and sometimes do lead to a malfunction of the system within which the receiver is employed.
The magnitude of temperatures attainable can readily be appreciated when it is recognized that solar powered systems which employ point focusing, cavity-type concentrators for powering Stirling engines optimally have a capability of withstanding pressures on the order of magnitude of 80 Atm and temperatures as high as 1400.degree. F.
Attempts have been made to solve these and similar problems through the use of numerous devices such as heat pipes provided for coupling solar flux receivers to heat operated engines, as more fully described in application Ser. No. 824,024, filed Aug. 12, 1977, now U.S. Pat. No. 4,135,367. While the devices of the prior art may function satisfactorily for their intended purposes, it is apparent that improvements are required before totally satisfactory solutions are provided for the numerous and complex problems now facing designers of devices intended to utilize a solar source of energy.
It is, therefore, the general purpose of the instant invention to provide an improved solar energy receiver for use in combination with a Stirling engine, adapted to relieve the cavity of a receiver of excessive thermal flux loading in the event heat loads resulting from flux density cannot be transferred from the receiver to a working fluid at a sufficiently high rate necessary to protect the system within which the receiver is incorporated.